Transcript Operant Conditioning

Operant Conditioning
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Operant Conditioning→ a form of learning in
which responses come to be controlled by their
consequences
– Learning occurs because responses come to be
influenced by outcomes that follow them
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Differences between classical and operant
conditioning:
Classical Conditioning
Operant Conditioning
An organism associates
different stimuli that it does
not control; associations are
formed between stimuli
Tends to involve reflexive,
involuntary responses
The organism associates its
behaviors with
consequences
Involves respondent
behavior- behavior that
occurs as an automatic
response to some stimulus
Involves operant behaviorbehavior that operates on
the environment producing
consequences
Tends to involve governed
voluntary responses
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Similarities between classical
and operant conditioning
Both involve acquisition, extinction,
spontaneous recovery, generalization and
discrimination
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Thorndike’s Law of Effect
Law of effect→ if a response in the
presence of a stimulus leads to satisfying
effects, the association between the
stimulus and the response is strengthened
– Behavior followed by favorable consequences
become more likely and behaviors followed by
unfavorable consequences become less likely
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B.F. Skinner
Demonstrated that organisms tend to
repeat those responses that are followed
by favorable consequences
Operant chamber, or Skinner box→ a
small enclosure in which an animal can
make a specific response that is recorded
while the consequences of the response
are systematically controlled
– Pigeons peck a small disk on the wall for food
– Rats press a lever for food
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Rate of key
pecking or lever
pressing is
continuously
monitored by a
device known as a
cumulative
recorder
Cumulative recordercreates a graphic
record of responding
and reinforcement in
a Skinner box as a
function of time
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Terminology
Reinforcement contingencies→ the
circumstances or rules that determine
whether responses lead to the
presentation of reinforcers
Reinforcement→ occurs when an event
following a response increases an
organism’s tendency to make that
response
– Strengthening of a response tendency
– Defined in terms of its effects on behavior
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Basic Processes in Operant
Conditioning
Acquisition→ refers to the initial stage of
learning some new pattern of responding
– Responding gradually increases because of
reinforcement, possibly through shaping
– Shaping→ reinforcement of closer and closer
approximations of a desired response
Used to train animals to do impressive tricks
Used when an organism, on its own, does not emit
the desired response
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Shaping
Shaping used to teach rats to press the lever
Skinner trained some pigeons so that they
appeared to play ping-pong
Priscilla the Fastidious Pig turned on a radio ,
ate at a kitchen table, put dirt clothes in a
hamper, ran a vacuum, and “went shopping”
with a shopping cart.
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Extinction→ the gradual weakening and
disappearance of a response tendency
because the response tendency is no
longer followed by a reinforcer
– Responding gradually slows and stops after
reinforcement is terminated
– Resistance to extinction→ occurs when an
organism continues to make a response after
delivery of the reinforcer has been terminated
Depends on the schedule of reinforcement
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Extinction
Extinction begins when previously
available reinforcement is stopped
– A brief surge in responding is followed by a
gradual decline
– Resistance to extinction important when
Studying doesn’t lead to reinforcement
Casino owners want to see in patrons so they
continue to gamble even when losing
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Stimulus Control: Generalization and
Discrimination
Discriminative stimuli→ cues that influence operant
behavior by indicating the probable consequences
(reinforcement or nonreinforcement) of a response
– When a response is consistently followed by a reinforcer in
the presence of a particular stimulus, that stimulus comes
to serve as a “signal” indicating that the response is likely
to lead to a reinforcer
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Discrimination Examples
Pigeons disk pecking may only be
reinforced when light turns on
– Discriminative stimuli = light
Birds learn that hunting for worms is likely
to be reinforced after rain
– Discriminative stimuli = rain
Ask parents for money when they are in a
good mood
– Discriminative stimuli = good mood
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Stimulus generalization→ an organism’s responding to
stimuli other than the original stimulus used in
conditioning
– Responding increases in the presence of new stimulus that
resembles original discriminative stimulus
– Example- Cat running into kitchen at the sound of the blender or
the can opener
Stimulus discrimination→ an organism’s lack of
response to stimuli that are similar to the original
stimulus used in conditioning
– Responding does not increase in the presence of new stimulus
that resembles original discriminative stimulus
– Example- Cat would respond only to the can opener, not the
blender
..\UltraGet\YouTube\Can opener cat call.mp4
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Reinforcement: Consequences that
Strengthen Responses
Positive reinforcement→ occurs when a response
is strengthened because it is followed by the
presentation of a rewarding stimulus.
– Examples- Good grades, tasty meals, pay checks,
scholarships, promotions, cars, attention, flattery
Negative reinforcement→ occurs when a response
is strengthened because it is followed by the
removal of an aversive (unpleasant) stimulus
– Remember: In this case, negative does not mean bad.
You want negative reinforcement.
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Negative reinforcement
Be careful not to confuse negative
reinforcement and punishment!!!
– Negative reinforcement increases behavior!
– Example- When a rat is in a Skinner box, a
moderate shock is delivered. If the rat presses the
lever, they are negatively reinforced by having the
shock turned off
– Example- If you clean to get rid of the mess, take
aspirin to relieve a headache,give in to a child’s
begging to stop the whining, give in to a roommate
or spouse to end an unpleasant argument
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Negative Reinforcement and
Avoidance Behavior
Escape learning→ an organism acquires a response that
decreases or ends some aversive stimulation
– Animals can learn to escape shock by running to an
additional compartment
– If you leave a party where you were getting picked on by
peers
Avoidance learning→ an organism acquires a response
that prevents some aversive stimulation from occurring
– Makes it hard to get rid of phobias
– If a light signals shock, animals learn to run to a safe
compartment as soon as the light comes on
– If you quit going to parties because of your concern about
being picked on
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Delayed reinforcement
– A favorable outcome is much more likely to
strengthen a response if the outcome follows
immediately
– Longer the delay between the designated
response and the delivery of the reinforcer,
the more slowly conditioning proceeds
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Conditioned Reinforcement
Primary reinforcers→ events that are inherently
reinforcing because they satisfy biological needs;
unlearned
– Food, water, warth, sex,
possibly affection expressed
through hugging/ close bodily contact
Secondary, or conditioned reinforcers→ events that
acquire reinforcing qualities by being associated with
primary reinforcers
– Money, good grades, attention,
flattery, praise, applause,
stylish clothes, sports cars
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Schedules of Reinforcement
Schedule of reinforcement→ determines which
occurrences of a specific response result in the
presentation of a reinforcer
Continuous reinforcement→ every instance of a
designed response is reinforced
– Fastest acquisition of a response
– Often used to shape and establish a new response
before moving to more realistic chedules
Intermittent, or partial reinforcement→ when a
designated response is reinforced only some of the time
– Makes a response more resistant to extinction;
organisms continue to respond long after removal of
reinforcers
Occasionally reinforcing a child’s tantrums can make them very
durable and difficult to eliminate
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Ratio Schedules
Ratio schedules→ require the organism to make the
designated response a certain number of times to gain
each reinforcer
Fixed-ratio (FR) schedules→ reinforcer is given after a
fixed number of nonreinforced responses
– Rat is reinforced for every 10th lever press
– Salesperson receives a bonus for every 4 cars sold
– Working on a piece meal basis
Variable-ratio (VR) schedule→ the reinforcer is given
after a variable number of non-reinforced responses
– Rat is reinforced for varying number of lever presses
– Slot machines
– Fly-fishing
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Interval Schedules
Interval schedule→ require a time period to pass between the
presentation of reinforcers
Fixed-interval (FI) schedule→ the reinforcer is given for the
first response that occurs after a fixed time interval has elapsed
– Rat is reinforced for first lever press after a two-minute interval
has elapsed and then must wait two minutes before being
reinforced again
– Checking to see if cookies are done
– Paid every two weeks
Variable-interval schedule→ reinforcer is given for the first
response after a variable time interval has elapsed
– Produces slow, steady responding
– A rat is reinforced for the first lever press after a 1 minute interval
has elapsed, but the following are 3 minutes, 2 minutes, 4 minutes
and so on
– Repeatedly dialing a busy number
– Checking your phone for an email or text
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– Regular fishing
Ratio schedules based on number of
responses
Interval schedules based on time
Ratio schedules produce a higher
response rate than interval schedules
Variable schedules produce more
consistent responding than fixed
schedules
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Punishment: Consequences that
Weaken Responses
Punishment→ occurs when an event following
a response weakens the tendency to make that
response
– Can trigger strong emotional responses including
anxiety, anger and resentment
– Physical punishment can often lead to an increase in
aggressive behavior
– Sometimes disciplinary goals can often be
accomplished more effectively by reinforcing
desirable behavior than by punishing undesirable
behavior
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Effective punishment
– Apply punishment swiftly
A delay in punishment tends to undermine its
impact
– Use punishment just severe enough to be
effective
– Make punishment consistent
– Explain the punishment
– Minimize dependence on physical punishment
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